In diagnosing and treating certain medical conditions, it is often desirable to perform a biopsy, in which a specimen or sample of tissue is removed for pathological examination, tests and analysis. A biopsy typically results in a biopsy cavity occupying the space formerly occupied by the tissue that was removed. As is known, obtaining a tissue sample by biopsy and the subsequent examination are typically employed in the diagnosis of cancers and other malignant tumors, or to confirm that a suspected lesion or tumor is not malignant. Treatment of cancers identified by biopsy may include subsequent removal of tissue surrounding the biopsy site, leaving an enlarged cavity in the patient's body. Cancerous tissue is often treated by application of radiation, by chemotherapy, or by thermal treatment (e.g., local heating, cryogenic therapy, and other treatments to heat, cool, or freeze tissue).
Cancer treatment may be directed to a natural cavity, or to a cavity in a patient's body from which tissue has been removed, typically following removal of cancerous tissue during a biopsy or surgical procedure. For example, U.S. Pat. No. 6,923,754 to Lubock and U.S. patent application Ser. No. 10/849,410 to Lubock, the disclosures of which are all hereby incorporated by reference in their entireties, describe devices for implantation into a cavity resulting from the removal of cancerous tissue which can be used to deliver irradiation to surrounding tissue. One form of radiation treatment used to treat cancer near a body cavity remaining following removal of tissue is “brachytherapy” in which a source of radiation is placed near to the site to be treated.
Lubock above describes implantable devices for treating tissue surrounding a cavity left by surgical removal of cancerous or other tissue that includes an inflatable balloon constructed for placement in the cavity. Such devices may be used to apply one or more of radiation therapy, chemotherapy, and thermal therapy to the tissue surrounding the cavity from which the tissue was removed. The delivery lumen of the device may receive a solid or a liquid radiation source. Radiation treatment is applied to tissue adjacent the balloon of the device by placing radioactive material such as radioactive “seeds” in a delivery lumen. Such treatments may be repeated if desired.
For example, a “MammoSite® Radiation Therapy System” (MammoSite® RTS, Proxima Therapeutics, Inc., Alpharetta, Ga. 30005 USA) includes a balloon catheter with a radiation source that can be placed within a tumor resection cavity in a breast after a lumpectomy. It can deliver a prescribed dose of radiation from inside the tumor resection cavity to the tissue surrounding the original tumor. The radiation source is typically a solid radiation source; however, a liquid radiation source may also be used with a balloon catheter placed within a body cavity (e.g., lotrex®, Proxima Therapeutics, Inc.). A radiation source such as a miniature or micro-miniature x-ray tube may also be used (e.g. U.S. Pat. No. 6,319,188). The x-ray tubes are small, flexible and are believed to be maneuverable enough to reach the desired treatment location within a patient's body. The radiation source is to be removed following each treatment session, or remains in place as long as the balloon remains within the body cavity. Inflatable treatment delivery devices and systems, such as the MammoSite® RTS and similar devices and systems (e.g., GliaSite® RTS (Proxima Therapeutics, Inc.)), are useful to treat cancer in tissue adjacent a body cavity.
Tissue cavities resulting from biopsy or other surgical procedures such as lumpectomy typically are not always uniform or regular in their sizes and shapes, so that radiation treatment often result in differences in dosages applied to different regions of surrounding tissue, including “hot spots” and regions of relatively low dosage. However, by conforming the tissue lining the cavity about an inflated member, such as a balloon, a more uniform or controlled radiation can be applied to the tissue.
The radiation balloon catheter is usually retained within the patient for about 5-10 days during which time radiation is emitted from a radiation source within the balloon. The proximal end of the catheter is preferably folded or coiled and secured onto or under the patient's skin during the retention period. However, in order to facilitate folding or coiling the catheter shaft, the shaft must be fairly flexible or it will be difficult to maintain in the folded or coiled configuration without subjecting the patient to discomfort. The catheter shaft is formed of low durometer polymeric material in order to improve flexibility but low durometer polymeric materials have high friction surfaces, making advancing a radiation source through a lumen of the catheter shaft difficult. Forming a soft polymeric material about a single tube with a lumen with greater lubricity is not difficult but forming a soft polymeric material with a plurality of lumens with greater lubricity is problematic.